For the purpose of preventing oxidation and performing long-term storing of various goods (objects to be stored) tending to be affected by oxygen and accordingly deteriorated or degraded, typified by, for example, food, beverages, pharmaceuticals and cosmetics, there have been used oxygen absorbing agents. The oxygen absorbing agents are used for removing the oxygen inside the vessels containing these goods.
As oxygen absorbing agents, from the viewpoint of the oxygen absorbing performance, easiness in handling and safety, there have generally been used oxygen absorbing agents including iron powder as the main reaction agent. However, such iron-based oxygen absorbing agents respond to metal detectors, and hence it has been difficult to perform foreign matter inspection by using metal detectors. Packages enclosing iron-based oxygen absorbing agents have possibility of ignition and hence cannot be heated with microwave ovens. In addition, iron-based oxygen absorbing agents take advantage of the oxidation reaction of iron powder, and hence exhibit the oxygen absorption effect thereof only for the objects to be stored which are high-moisture systems; thus, the objects of the iron-based oxygen absorbing agents are limited to the objects to be stored which are high-moisture systems.
By constituting vessels with multilayer materials provided with oxygen absorbing layers composed of oxygen-absorbing resin compositions prepared by mixing iron-based oxygen absorbing agents with thermoplastic resins, packaging vessels have been developed in such a way that the gas barrier property of the vessels is achieved and the oxygen absorption function is imparted to the vessels themselves (see Patent Document 1). However, such vessels also have a problem such that such vessels cannot be used for performing foreign matter inspection with metal detectors, cannot be heated with microwave ovens, and are adaptable only to the objects to be stored which are high-moisture systems. In addition, such vessels also suffer from a problem of insufficient internal visibility due to opacity.
From the aforementioned circumstances, oxygen absorbing agents including an organic substance as a main reaction agent are demanded. As the oxygen absorbing agent including an organic substance as a main reaction agent, an oxygen absorbing agent including ascorbic acid as the main agent is known (see Patent Document 2).
On the other hand, an oxygen-absorbing resin composition being composed of a resin and a transition metal catalyst and having an oxygen-capturing property is known. For example, a resin composition is known which is composed of a polyamide, in particular a xylylene group-containing polyamide as an oxidizable organic component and a transition metal catalyst; in addition, a resin composition having an oxygen-capturing function, and an oxygen absorbing agent, a packaging material, a multilayer laminated film for packaging obtained by molding such a resin composition are known (see Patent Document 3).
As an oxygen-absorbing resin composition requiring no moisture for oxygen absorption, an oxygen-absorbing resin composition composed of a resin having carbon-carbon unsaturated bonds and a transition metal catalyst is also known (see Patent Document 4).
In addition, as a composition to scavenge oxygen, a composition composed of a polymer including substituted cyclohexene functional group or a low molecular weight substance with the cyclohexene ring bonded thereto and a transition metal is known (see Patent Document 5).